1. Field of the Invention
The present invention relates to a ceramic electronic component, and more particularly, relates to an external electrode structure provided in a ceramic electronic component.
2. Description of the Related Art
In recent years, with a reduction in size and thickness of electronic devices, such as cell phones and portable music players, a reduction in size and thickness of ceramic electronic components which are installed in such electronic devices has also been advancing rapidly. Ceramic electronic components are usually mounted on wiring boards installed in electronic devices. With the reduction in size and thickness of ceramic electronic components, the strength of the ceramic electronic components tends to decrease.
For example, a ceramic electronic component illustrated in FIG. 1 of Japanese Unexamined Patent Application Publication No. 2009-146732 has a structure in which a base layer of each external electrode is formed by baking using a conductive paste having a specific composition, and a plating layer is formed thereon. In such a structure, stress generated during mounting easily concentrates on the tip portion of the external electrode including the plating layer, and cracks may occur, originating from the tip portion, in the ceramic electronic component in some cases. Description will be made more specifically with reference to FIG. 15.
FIG. 15 is a cross-sectional view schematically showing a monolithic ceramic capacitor 1 as an example of an existing ceramic electronic component, and is used to explain a problem caused by stress applied during mounting.
A ceramic body 2 included in the monolithic ceramic capacitor 1 has a first principal surface 3 and a second principal surface 4 which are opposed to each other, the second principal surface 4 being located on a mounting surface side. External electrodes 5 and 6 are disposed on both end portions of the ceramic body 2. When the monolithic ceramic capacitor 1 is mounted on a wiring board (not shown), the first principal surface 3 is held by suction using a suction head (not shown) of a mounter and mounted on the land of the wiring board. As shown in FIG. 15, stress due to inertia during mounting is applied to the first principal surface 3, and the point to which the stress is applied corresponds to a point of effort 7. Contact points between the wiring board and the first external electrode 5 and the second external electrode 6, which are disposed at both ends of the monolithic ceramic capacitor 1, serve as fulcrums 8 and 9, respectively. As a result, tips (surrounded by dotted lines) of portions of the external electrodes 5 and 6, which extend over the principal surface 4 on the mounting surface side, serve as points of load 10 and 11, respectively. Cracks tend to occur inside the ceramic body 2, originating from these points of load 10 and 11.
This phenomenon easily occurs when the principal surfaces 3 and 4 of the ceramic body 2 are parallel to the mounting surface, and in particular, with a reduction in height of the monolithic ceramic capacitor 1.